The Portable, CotmpleteElectrophoresis Appparatus

Perkin-Elmer Tiselius Rlectropho-resis Apparatus at the UniversityHospital of the New York Univer-sity-Bellevue Medical Center.

An ordinary laboratory bench, without specialmountings, is sufficient for the installation of ThePerkin-Elmer Tiselius Electrophoresis Apparatus.Precision-ground, achromatic schlieren opticsyield sharp, clear patterns. Qperating the instru-ment is so simple that highly trained personnelare not required-a single technician can readilyoperate two units. Measuring only 63 inches inlength, the entire unit weighs 120 pounds and isconstructed of heavy aluminum. It operates forseveral hundred hours under its own powersystem.The apparatus is shipped complete and pre-

focussed with a 2 cc Tiselius cell 50 mm long,

Schematic cutaway of the newPerkin-Elmer Model 38 TiseliusElectrophoresis Apparatus.

cell holder, ice bath and stirrer, silver-silverchloride electrodes, open-end 26 cc buffer bottles,stainless steel needles for filling, the cell, groundglass screen for visual observation of the pattern,and a 3'A"x 4Y4A film holder. Double knife-edgeand diagonal slit for use with a cylindrical lensare also included.The dependability, accuracy and simplicity of

The Perkin-Elmer Tiselius Electrophoresis Ap-paratus have made it the choice of hospital andresearch laboratories throughout the world.

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Leading manufacturers of Infrared Spectrometers, Continuous Infrarod Analyzer, UniversalMonochromator, Flame Photometr, Tlslius Electrophorees Appaiatus, D. C. Amplifien, andother electro-optical Insdtuments for analysis and research.

2NewEdition from SAUNDERS

New (2nd) Edition!Conant, Smiith, Baker, Callaway & MartinManual of Clinical MycologyThis useful manual gives a concise knowledge of the diagnosis and treatmnentof diseases of fungus origin. Brought completely up-to-date, it defines eachdisease; tells where it is found; explains source of infection, symptoms,methods of laboratory examination; differential diagnosis, and how to insti-tute proper treatment.All recent advances are included: use of antigens for detection of antibodiesin sera of patients having coccidiomycosis, histoplasmosis, etc.

By NoawA F. CONANT, Ph.D., Professor of Mycology, Duke University School of Medicine; DAVmTILLESON Smsrr, M.D., Professor of Bacteriology and Associate Professor 'of Medicine, Duke Uni-versity School of Medicine; ROOER D,N1o BAKER, M.D., Chief, Laboratory Service, VeteransAdministration Hospital, Durham, N. C.; jAsmp LAR CALAWAY, M.D., Professor of Dermatologyand Syphilology, Duke University School of Medicine; and DONALD STOVER MARTIN, M.D., Chief,Bacteriology Section, Communicable Disease Center, Chamblee, Georgia. About 430 pages. 5Ws' x 7N',202 illustrations. Now (2nd) Edition-Ready Soon!

New (2nd) Edition!Mackie, Hunter & Worth-Manual of Tropical MedicineThis book combines the basic material of a textbook of parasitology withclinical management of tropical diseases.For this New (2nd) Edition, it has been extensively revised to cover thedrastic changes in the diagnosis and treatment of tropical diseases which havetaken place in the past eight years. Original work of over 20 contributors isrepresented here.

By THOMAS T. MACKiE, M.D., Colonel, M.C., A.U.S. (Retired); Chairman, The American Founda-tion for Tropical Medicine; GEORGE W. HUNTER, III, Ph.D., Colonel, M.S.C., U.S.A.; Chief, Sectionof Parasitology-Entomology, Fourth Army Area Medical Laboratory, Brooke Army Medical Center,Fort Sam Houston, Texas; and C. BRooKE WORTH, M.D., Field Staff Member, Division of Medicineand Public Health, The Rockefeller Foundation. About 918 pages, 6"x9", 304 illustrations.

New (2nd) Edition-Ready in March.

W. B. SAUNDERS COMPANYWest Washington Square Philadelphia 5

January 8, 1954 1A

Hlere's a-new automatic scler, onrdi-circuitS et co r g the lattkadvances t.TeM oddel 183 "Coun t"Mcurately counts the pulses from a G-M Or sciatilolation detectr, mer the length of time re-quiredto ,Cum pr mined- number ofthese pulsesj and-supplies S500to2500 volts forthe detector.'The instrument- can.be 'ised as a conventionalscaler with the counting time manually controlledby the operator, or exclusive "Countm0OMatic'.and- scale selector controls permit 1i-pd:mined count settings from 40 to 256,000coIn addition, the counting-tPe pa -eperiods ranging from 2 nds , !the use of Model Ti Dual iuner. Thesr willthen indicate the number ;of di ncorded during this time interval.

Total count is micat io asily read register,wZhile-tt li1t-ln : -automatically indicateseIaps cou,-ftft te;t 9999.99 minutes. A sim-gle sswith oc e10ctrical reset of the register,ter, adianitn lamps.

h*t44bechosen whenever automatic:4~t~t ncounting is advantageous.

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SCIENCE, Vol. 119

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For the Deternination of IronA new sensitive, stable, and widely applicable reagent, de-veloped by John H. Yoe and A. Letcher Jones, Universityof Virginia (Reference-Industrial and Engineering Chem-istry, Analytical Edition, Vol. 16, p. 111-115, 1944), forthe colorimetric determination of ferric iron. The reagentmay be used in either acid or alkaline medium. In alkalinemedium it is sensitive to one part of iron in 100,000,000parts of solution. In acid solution the sensitivity is onepart in 30,000,000.

For the Deternination of TITANIUM(Method of Yoe & Armstrong)

TIRON is an extremely sensitive reagent for the determi-nation of TITANIUM (indicated sensitivity, 1 part ofTITANIUM in 100,000,000 parts of solution). Only afew ions interfere. Furthermore, TIRON may be usedto determine both Titanium and Iron in same solution.TIRON REAGENT available from stock.

For the Determination of Molybdenumby Fritz Will and John H. Yoe

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Used successfully for colorimetric determination of Molyb-denum in steels and other materials. Practical sensitivity of0.1 ppm. Molybdenum.

LaMotte Chemical Products CompanyDept. "H" Towson 4, Md.

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SCIENCE, Vol. 119

PHOTOVOLT Densitometerfor

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